Lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, preparation and application

Abstract

The invention provides a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, preparation and application, the lignin-based flame-retardant bacterial cellulose gel polymer electrolyte is prepared by compounding a modified lignin material, a composite lithium salt and bacterial cellulose, when the polymer electrolyte is greater than or equal to 700 DEG C, the carbon residue rate is greater than or equal to 49.52%, the heat release rate peak value is less than or equal to 61.12 kW m <-2 >, and the flame-retardant bacterial cellulose gel polymer electrolyte has a good flame-retardant effect. The smoke release rate peak value is less than or equal to 0.0089 m < 2 > s <-1 >, and T5 is greater than or equal to 246.9 DEG C. Under the condition of room temperature, the ionic conductivity of the gel polymer electrolyte is 2.37-5mS cm <-1 >, the lithium ion transference number is greater than or equal to 0.75, and the electrochemical window is greater than or equal to 4.87 V (vs Li < + > / Li); in addition, when the temperature is less than or equal to-20 DEG C, the ionic conductivity is more than or equal to 0.162 mS cm <-1 >. The lignin-based flame-retardant bacterial cellulose gel polymer electrolyte not only has an excellent flame-retardant effect, but also has relatively good electrochemical performance.

Description

Technical Field

[0001] The invention belongs to the field of polymer electrolytes, and in particular relates to a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, and its preparation and application. Background Art

[0002] With the rapid development of new energy technologies, the demand for high-performance and high-safety energy storage devices is growing. In the field of lithium-ion batteries, electrolytes are key components of batteries, and their performance directly affects the overall performance and safety of the batteries. Although traditional liquid electrolytes have high ionic conductivity, they have safety hazards such as easy leakage and flammability, which limit their application in some special fields. Although solid polymer electrolytes have excellent performance in terms of safety, their low ionic conductivity and poor interfacial compatibility restrict their further development. Quasi-solid electrolytes include gel polymer electrolytes and composite polymer electrolytes. Quasi-solid electrolytes, as a new type of electrolyte material between liquid and solid, have attracted widespread attention in the academic community. However, it is difficult for this electrolyte to simultaneously achieve high mechanical properties, thermal stability, high flame retardant properties, high conductivity and low-temperature applications. Therefore, how to simultaneously improve the mechanical properties, thermal stability, high flame retardant properties, high conductivity and low-temperature applications while ensuring the high conductivity of gel polymer electrolytes is a technical problem that needs to be solved urgently. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, and its preparation method comprises the following steps:

[0004] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water at a mass ratio of 1:5 to 5:1, wherein the concentration of hydroxyapatite in the solution is 0.01 to 0.1 g mL -1 , magnetically stirring at room temperature for 12 to 40 hours, vacuum filtering, washing, and drying for 5 to 20 hours, and calcining at 180 to 400° C. for 1 to 10 hours to obtain lithiated hydroxyapatite;

[0005] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix and disperse lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose in ethanol according to a mass ratio of 4.4 - 15.6:4.4 - 15.6:15:65 - 75. Stir with a homogenizer at a rotation speed of 8000 - 10000 rpm for 0.5 - 2 h at room temperature to obtain a paste. Then, vacuum dry the paste for 2 - 3.5 h and roll press it at 8 - 11 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness. Immerse the polymer electrolyte in vinyl fluorocarbon / difluoroethyl acetate to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, where the volume ratio of vinyl fluorocarbon to difluoroethyl acetate is 1:2 - 2:1. When the polymer electrolyte is at ≥700 °C, the char residue rate is ≥49.52%, the peak heat release rate is ≤61.12 kW m -2 and the peak smoke release rate is ≤0.0089 m 2 s -1 , T5 ≥ 246.9 °C. At room temperature, the ionic conductivity of the gel polymer electrolyte is 2.37 - 5 mS cm -1 , the lithium ion transference number is ≥0.75, and the electrochemical window is ≥4.87 V (vs Li + / Li); at ≤ -20 °C, the ionic conductivity is ≥0.162 mS cm -1 ;

[0006] The modified lignin in step (2) is LNDP or LMA;

[0007] The preparation method of the LNDP includes the following steps:

[0008] Take sodium lignosulfonate and add it to deionized water to prepare an aqueous sodium lignosulfonate solution with a concentration of 0.07 - 0.5 g mL -1 . Add urea to formaldehyde to prepare a urea-formaldehyde solution with a concentration of 0.2 - 1 g mL -1 . Then add the aqueous sodium lignosulfonate solution to the urea-formaldehyde solution and mix well. The mass ratio of sodium lignosulfonate to urea is 1:3 - 1:1. React at 25 - 100 °C for 1 - 8 h, cool, add a 0.5 - 5 mol L -1 HCl aqueous solution to adjust the solution to be weakly acidic, and then obtain LSN through suction filtration, washing with deionized water, and drying. Mix LSN and p-hydroxybenzaldehyde in ethanol according to a mass ratio of 1:2 - 1.1:1, where the concentration of LSN is 0.06 - 0.45 g mL -1, heat at 45 - 80 °C for 0.5 - 5 hours, then cool, filter, wash with ethanol, and dry to obtain LND powder; add LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:2.5 - 2:1 to tetrahydrofuran, where the concentration of LND is 0.06 - 0.8 g / mL -1 , react at 10 - 50 °C for 6 - 30 h, then filter, wash with tetrahydrofuran, and dry under vacuum to obtain LNDP;

[0009] The preparation method of the described LMA includes the following steps:

[0010] Mix enzymatically hydrolyzed lignin and melamine in a mass ratio of 1:2.5 - 2.5:1 in N,N-dimethylformamide, where the concentration of enzymatically hydrolyzed lignin in N,N-dimethylformamide is 0.02 - 0.1 g / mL -1 , magnetically stir at 50 - 150 °C for 1 - 8 h, then add a N,N-dimethylformamide solution of aminotrimethylenephosphonic acid with a concentration of 0.1 - 0.8 g / mL -1 , where the mass ratio of enzymatically hydrolyzed lignin to aminotrimethylenephosphonic acid is 1:5 - 1:2, continue to magnetically stir for 2 - 15 h, cool to room temperature, stir for 20 - 60 minutes, then wash with ethanol and dry to obtain LMA.

[0011] Further, in step (1), mix hydroxyapatite powder and lithium fluoride in a mass ratio of 1:2 - 2:1 in deionized water, where the concentration of hydroxyapatite in the solution is 0.01 - 0.02 g / mL -1 , magnetically stir at room temperature for 24 - 36 h, vacuum filter, wash, and dry for 10 - 12 hours, then calcine at 200 - 350 °C for 2 - 4.5 hours to obtain lithiated hydroxyapatite;

[0012] Further, the preparation method of the described LNDP includes the following steps:

[0013] Take sodium lignosulfonate and add it to deionized water to prepare a sodium lignosulfonate aqueous solution with a concentration of 0.071 - 0.125 g / mL -1 Prepare a urea-formaldehyde solution by adding urea to formaldehyde with a concentration of 0.25 - 0.50 g / mL -1 , then add the sodium lignosulfonate aqueous solution to the urea-formaldehyde solution and mix well. The mass ratio of sodium lignosulfonate to urea is 1:2.12 - 1:1.06. React at 30 - 65 °C for 2 - 4 h, then cool, and add 1 - 2 mol / L -1The HCl aqueous solution is adjusted to be weakly acidic, and then LSN is obtained through suction filtration, washing with deionized water, and drying. LSN and p-hydroxybenzaldehyde are mixed in ethanol at a mass ratio of 1:1.2 to 1:1.1, where the concentration of LSN is 0.071 - 0.125 g / mL -1 , and it is kept warm at 50 - 65 °C for 1 - 3 hours. After cooling, filtering, washing with ethanol, and drying, LND powder is obtained; LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are added to tetrahydrofuran at a mass ratio of 1:1.85 to 1.08:1, where the concentration of LND is 0.083 - 0.16 g / mL -1 , and the reaction is carried out at 10 - 25 °C for 8 - 24 h. After filtering, washing with tetrahydrofuran, and vacuum drying, LNDP is obtained;

[0014] Furthermore, the preparation method of the LMA includes the following steps:

[0015] Enzymatic lignin and melamine are mixed in N,N-dimethylformamide at a mass ratio of 1:1.94 to 1.37:1, where the concentration of enzymatic lignin in N,N-dimethylformamide is 0.033 - 0.087 g / mL -1 , and after magnetic stirring at 60 - 110 °C for 2 - 4 h, a N,N-dimethylformamide solution of aminotrimethylenephosphonic acid with a concentration of 0.20 - 0.60 g / mL -1 is added, where the mass ratio of enzymatic lignin to aminotrimethylenephosphonic acid is 1:3.47 to 1:2.31. Continue magnetic stirring for 6 - 10 h, cool to room temperature, stir for 30 - 55 minutes, then wash with ethanol and dry to obtain LMA.

[0016] The present invention also provides the application of the lignin-based flame-retardant bacterial cellulose gel polymer electrolyte in the field of batteries.

[0017] Advantages of the present invention:

[0018] Compared with the prior art, through the coordinated regulation of raw materials, raw material ratios, processes, and process parameters, the present invention has the following advantages:

[0019] Compared with the existing lithium salt polymer electrolytes, the polymer electrolyte obtained by the present invention has significantly improved flame retardancy, lithium ion transference number, thermal stability, conductivity, and mechanical properties simultaneously: Firstly, in terms of flame retardancy: the peak heat release rate ≤ 61.12 kW / m -2 , compared with the peak heat release rate of the lithium salt polymer electrolyte obtained by the prior art (≥ 298.74 kW / m -2 ), it has decreased by 80%; the peak smoke release rate ≤ 0.0089 m 2 / s -1, compared with the peak value of the smoke release rate of the lithium salt polymer electrolyte obtained by the prior art (≥0.0138 m 2 s -1 ), it decreased by 36%. In addition, for the polymer electrolyte obtained in the present invention, when the temperature is ≥700 °C, the char residue rate is ≥49.52%. Therefore, the electrolyte obtained in the present invention has significant advantages in flame retardancy. Second, from the perspective of the lithium ion transference number: the lithium ion transference number of the polymer electrolyte obtained in the present invention at room temperature is ≥0.75, and the electrochemical window is ≥4.87 V (vs Li + / Li), which is higher than that of the polymer electrolyte in the prior art (≤0.54). Third, from the perspective of ionic conductivity, the ionic conductivity of the polymer electrolyte obtained in the present invention is 2.37 - 5 mS cm -1 , which is much higher than the conductivity of the solid polymer electrolyte in the prior art (10 -4 - 10 -2 mS cm -1 ). In addition, the polymer electrolyte obtained in the present invention breaks through the technical bottleneck of the significant decrease in low-temperature conductivity in the prior art and can still maintain a high ionic conductivity at low temperatures. For example, at -20 °C, the ionic conductivity of the polymer electrolyte obtained in the present invention is ≥0.162 mS cm -1 , showing excellent electrochemical performance. Fourth, from the perspective of thermal stability, the T5 of the polymer electrolyte obtained in the present invention is ≥246.9 °C, enabling the polymer electrolyte to have good thermal stability at the same time. Fifth, from the perspective of mechanical properties, the tensile strength of the polymer electrolyte obtained in the present invention is ≥19.8 MPa. In summary, the raw materials used in the present invention have low cost, are environmentally friendly raw materials from nature, reduce the amount of raw material addition, and simplify the process. The obtained lignin-based flame-retardant bacterial cellulose gel polymer electrolyte simultaneously improves the flame retardancy, electrochemical performance, thermal stability, and tensile strength, has good application prospects in the field of lithium-ion batteries, is suitable for industrial production, and breaks through the technical bottleneck that it is difficult to simultaneously improve any two, three, or more of the flame retardancy, electrochemical performance, room-temperature and low-temperature conductivity, thermal stability, and tensile strength of the polymer electrolyte in the prior art. Detailed Embodiments

[0020] The present invention will be further elaborated through specific embodiments below. These embodiments are only for illustrating the present invention and are not used to limit the protection scope of the claims of the present invention.

[0021] Example 1

[0022] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to a mass ratio of 2:1, where the concentration of hydroxyapatite in the solution is 0.02 g mL -1, magnetically stirred at room temperature for 24 h, vacuum filtered, washed, and dried for 12 h, then calcined at 300 °C for 3 h to obtain lithiated hydroxyapatite;

[0023] (2) The paste-like bacterial cellulose slurry was washed and dried with deionized water. Lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose were mixed and dispersed in ethanol according to the mass ratio of 10:10:15:65, and stirred at 10000 rpm for 1 h at room temperature using a homogenizer to obtain a paste. Then the paste was vacuum dried for 3 h and roll-pressed at 10 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a film; The polymer electrolyte was immersed in fluoroethylene carbonate / ethyl difluoroacetate (v / v = 1:1) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a film. The peak heat release rate of the BC / Li-FR polymer electrolyte is 61.12 kW m -2 , the char residue rate is 49.52% at 700 °C, and the peak smoke release rate is 0.0089 m 2 s -1 , the T5 of this polymer electrolyte is 270 °C, the tensile strength is 25 MPa, and the ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 4.69 mS cm -1 , Li + transference number is 0.75, the electrochemical window is 4.87 V (vs Li + / Li), and in addition, at -20 °C, the ionic conductivity is 0.162 mS cm -1 ;

[0024] The preparation method of the modified lignin (hereinafter referred to as LNDP1) described in step (2) includes the following steps:

[0025] Sodium lignosulfonate was taken and added to deionized water to prepare an aqueous sodium lignosulfonate solution with a concentration of 0.071 g mL -1 of the aqueous sodium lignosulfonate solution, urea was added to formaldehyde to prepare a urea-formaldehyde solution with a concentration of 0.50 g mL -1 of the urea-formaldehyde solution, and then the aqueous sodium lignosulfonate solution was added to the urea-formaldehyde solution and mixed thoroughly. The mass ratio of sodium lignosulfonate to urea is 1:2.12. After reacting at 55 °C for 3.5 h, it was cooled, and 2 mol L -1 of HCl aqueous solution was added to adjust the solution to be weakly acidic, and then obtained LSN by suction filtration, washing with deionized water, and drying. LSN and p-hydroxybenzaldehyde were mixed in ethanol according to the mass ratio of 1:1.10, and the concentration of LSN is 0.125 g mL-1 , keep it at 60 °C for 3 hours, then cool, filter, wash with ethanol, and dry to obtain LND powder; Add LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to tetrahydrofuran according to a mass ratio of 1.08:1, where the concentration of LND is 0.16 g / mL -1 , react at 15 °C for 12 h, then filter, wash with tetrahydrofuran, and dry in vacuum to obtain LNDP1.

[0026] Example 2

[0027] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to a mass ratio of 1:1, where the concentration of hydroxyapatite in the solution is 0.02 g / mL -1 , stir magnetically at room temperature for 24 h, vacuum filter, wash, and dry for 12 hours, then calcine at 350 °C for 4 hours to obtain lithiated hydroxyapatite;

[0028] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), modified lignin, and the paste-like bacterial cellulose in ethanol according to a mass ratio of 4.4:15.6:15:65, and stir with a homogenizer at 8000 rpm at room temperature for 1.5 h to obtain a paste. Then vacuum dry the paste for 3 h and roll press it at 9 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with a uniform thickness, named BC / Li-FR polymer electrolyte, in the form of a film; Immerse the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 1:2) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, in the form of a film. The T5 of this polymer electrolyte is 246.9 °C, the tensile strength is 19.8 MPa, and the ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 2.75 mS / cm -1 ,

[0029] The preparation method of the modified lignin (hereinafter referred to as LNDP2) described in step (2) includes the following steps:

[0030] Take sodium lignosulfonate and add it to deionized water to prepare an aqueous sodium lignosulfonate solution with a concentration of 0.125 g / mL -1 Add urea to formaldehyde to prepare a urea-formaldehyde solution with a concentration of 0.50 g / mL -1 of the urea-formaldehyde solution, then add the aqueous sodium lignosulfonate solution to the urea-formaldehyde solution and mix well. The mass ratio of sodium lignosulfonate to urea is 1:1.06. After reacting at 40 °C for 3 h, cool, and add 1.5 mol / L -1The HCl aqueous solution was adjusted to be weakly acidic, and then LSN was obtained through suction filtration, washing with deionized water, and drying. LSN and p-hydroxybenzaldehyde were mixed in ethanol at a mass ratio of 1:2, and the concentration of LSN was 0.1 g / mL -1 , and kept at 60 °C for 3 hours. After cooling, filtering, washing with ethanol, and drying, LND powder was obtained; LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to tetrahydrofuran at a mass ratio of 1.08:1, and the concentration of LND was 0.125 g / mL -1 , and reacted at 20 °C for 8 h. After filtration, washing with tetrahydrofuran, and vacuum drying, LNDP2 was obtained.

[0031] Example 3

[0032] (1) Hydroxyapatite powder and lithium fluoride were mixed in deionized water at a mass ratio of 1:1, and the concentration of hydroxyapatite in the solution was 0.0125 g / mL -1 , and magnetically stirred at room temperature for 36 h. After vacuum filtration, washing, and drying for 10 hours, it was calcined at 350 °C for 4 hours to obtain lithiated hydroxyapatite;

[0033] (2) The paste-like bacterial cellulose slurry was washed and dried with deionized water. Lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose were mixed and dispersed in ethanol at a mass ratio of 15.6:4.4:15:65. After stirring with a homogenizer at 9000 rpm for 1.5 h at room temperature, a paste was obtained. Then the paste was vacuum dried for 2.5 h and roll-pressed at 10 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness, named BC / Li-FR polymer electrolyte, in the form of a film; the polymer electrolyte was soaked in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 2:1) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature was 2.37 mS / cm -1 ,

[0034] The preparation method of the modified lignin (hereinafter referred to as LNDP3) described in step (2) includes the following steps:

[0035] Sodium lignosulfonate was taken and added to deionized water to prepare an aqueous solution of sodium lignosulfonate with a concentration of 0.125 g / mL -1 , and urea was added to formaldehyde to prepare an aqueous solution with a concentration of 0.38 g / mL -1of the urea formaldehyde solution, and then add the sodium lignosulfonate aqueous solution to the urea formaldehyde solution and mix well. The mass ratio of sodium lignosulfonate to urea is 1:1.59. After reacting at 30 °C for 3 h, cool it, and add 1 mol L -1 of HCl aqueous solution to adjust the solution to be weakly acidic, and then obtain LSN through suction filtration, washing with deionized water and drying. LSN and p-hydroxybenzaldehyde are mixed in ethanol according to a mass ratio of 1:1, and the concentration of LSN is 0.1 g mL -1 , keep it warm at 50 °C for 2 hours, and then obtain LND powder after cooling, filtering, washing with ethanol and drying; Add LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to tetrahydrofuran according to a mass ratio of 1.08:1, and the concentration of LND is 0.14 g mL -1 , react at 20 °C for 24 h, and then obtain LNDP3 after filtration, washing with tetrahydrofuran and vacuum drying.

[0036] Example 4

[0037] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to a mass ratio of 1:1, and the concentration of hydroxyapatite in the solution is 0.0125 g mL -1 , stir magnetically at room temperature for 36 h, vacuum filter, wash and dry for 10 hours, and then calcine at 350 °C for 2 hours to obtain lithiated hydroxyapatite;

[0038] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix and disperse lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin and the paste-like bacterial cellulose in ethanol according to a mass ratio of 5:5:15:75, and use a homogenizer to stir at a speed of 10000 rpm for 0.5 h at room temperature to obtain a paste. Then vacuum dry the paste for 3.5 h and roll press it at 9 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a membrane; Immerse the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 2:1) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a membrane. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 2.79 mS cm -1 ,

[0039] The preparation method of the modified lignin (hereinafter referred to as LNDP4) in step (2) includes the following steps:

[0040] Take sodium lignosulfonate and add it to deionized water to prepare a solution with a concentration of 0.083 g mL -1An aqueous solution of sodium lignosulfonate, add urea to formaldehyde to prepare a urea-formaldehyde solution with a concentration of 0.25 g / mL -1 of urea-formaldehyde solution, then add the aqueous solution of sodium lignosulfonate to the urea-formaldehyde solution and mix well. The mass ratio of sodium lignosulfonate to urea is 1:1.06. After reacting at 50 °C for 2 h, cool it, add 2 mol / L -1 of HCl aqueous solution to adjust the solution to be weakly acidic, then filter, wash with deionized water and dry to obtain LSN. Mix LSN and p-hydroxybenzaldehyde in ethanol according to a mass ratio of 1:1.10, where the concentration of LSN is 0.083 g / mL -1 , keep it warm at 55 °C for 2 hours, then cool, filter, wash with ethanol and dry to obtain LND powder; add LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to tetrahydrofuran according to a mass ratio of 1:1.39, where the concentration of LND is 0.10 g / mL -1 , react at 25 °C for 12 h, then filter, wash with tetrahydrofuran and vacuum dry to obtain LNDP4.

[0041] Example 5

[0042] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to a mass ratio of 1:2, where the concentration of hydroxyapatite in the solution is 0.01 g / mL -1 , stir magnetically at room temperature for 24 h, vacuum filter, wash and dry for 12 hours, then calcine at 200 °C for 4.5 hours to obtain lithiated hydroxyapatite;

[0043] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin and the paste-like bacterial cellulose in ethanol according to a mass ratio of 4.4:15.6:15:65, and stir with a homogenizer at 8500 rpm for 0.5 h at room temperature to obtain a paste. Then vacuum dry the paste for 3 h and roll press it at 11 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a film; immerse the polymer electrolyte in fluoroethylene carbonate / ethyl difluoroacetate (v / v = 2:1) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 3.14 mS / cm -1 ,

[0044] The preparation method of the modified lignin (hereinafter referred to as LNDP5) in step (2) includes the following steps:

[0045] Sodium lignosulfonate was added to deionized water to prepare an aqueous solution of sodium lignosulfonate with a concentration of 0.071 g / mL. -1 Urea was added to formaldehyde to prepare a urea-formaldehyde solution with a concentration of 0.50 g / mL. -1 Then, the aqueous solution of sodium lignosulfonate was added to the urea-formaldehyde solution and mixed thoroughly. The mass ratio of sodium lignosulfonate to urea was 1:2.12. After reacting at 50 °C for 2 h, it was cooled, and 1 mol / L -1 HCl aqueous solution was added to adjust the solution to be weakly acidic. Then, it was filtered, washed with deionized water, and dried to obtain LSN. LSN and p-hydroxybenzaldehyde were mixed in ethanol according to a mass ratio of 1:1.10, and the concentration of LSN was 0.071 g / mL. -1 It was kept warm at 60 °C for 1 h, then cooled, filtered, washed with ethanol, and dried to obtain LND powder. LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to tetrahydrofuran according to a mass ratio of 1:1.39, and the concentration of LND was 0.083 g / mL. -1 It was reacted at 10 °C for 10 h, then filtered, washed with tetrahydrofuran, and dried in vacuo to obtain LNDP5.

[0046] Example 6

[0047] (1) Hydroxyapatite powder and lithium fluoride were mixed in deionized water according to a mass ratio of 1:2, and the concentration of hydroxyapatite in the solution was 0.0125 g / mL. -1 It was magnetically stirred at room temperature for 36 h, vacuum filtered, washed, and dried for 12 h, and then calcined at 350 °C for 4 h to obtain lithiated hydroxyapatite.

[0048] (2) The paste-like bacterial cellulose slurry was washed and dried with deionized water. Lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), modified lignin, and the paste-like bacterial cellulose were mixed and dispersed in ethanol according to a mass ratio of 4.4:15.6:15:65. It was stirred at 9500 rpm for 2 h at room temperature using a homogenizer to obtain a paste. Then, the paste was dried in vacuo for 3.5 h and roll-pressed at 10 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with a uniform thickness, named BC / Li-FR polymer electrolyte, which existed in the form of a film. The lignin-based flame-retardant bacterial cellulose gel polymer electrolyte was obtained by soaking the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 1:2), named BC / Li-FR gel polymer electrolyte, which existed in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature was 3.09 mS / cm. -1 ,

[0049] The preparation method of the modified lignin (hereinafter referred to as LNDP6) described in step (2) includes the following steps:

[0050] Take sodium lignosulfonate and add it to deionized water to prepare an aqueous sodium lignosulfonate solution with a concentration of 0.091 g / mL -1 Take urea and add it to formaldehyde to prepare a urea-formaldehyde solution with a concentration of 0.38 g / mL -1 Then add the aqueous sodium lignosulfonate solution to the urea-formaldehyde solution and mix well. The mass ratio of sodium lignosulfonate to urea is 1:1.59. After reacting at 65 °C for 4 h, cool it, add 2 mol / L -1 HCl aqueous solution to adjust the solution to be weakly acidic, then filter, wash with deionized water and dry to obtain LSN. Mix LSN and p-hydroxybenzaldehyde in ethanol according to a mass ratio of 1:1.10, where the concentration of LSN is 0.091 g / mL -1 , keep it warm at 65 °C for 2 hours, then cool, filter, wash with ethanol, and dry to obtain LND powder; Add LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to tetrahydrofuran according to a mass ratio of 1.08:1, where the concentration of LND is 0.091 g / mL -1 , react at 15 °C for 12 h, then filter, wash with tetrahydrofuran, and vacuum dry to obtain LNDP6.

[0051] Example 7

[0052] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to a mass ratio of 1:1, where the concentration of hydroxyapatite in the solution is 0.01 g / mL -1 , stir magnetically at room temperature for 24 h, vacuum filter, wash, and dry for 12 hours, then calcine at 300 °C for 2 hours to obtain lithiated hydroxyapatite;

[0053] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix and disperse lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose in ethanol according to the mass ratio of 4.4:15.6:15:65. Stir with a homogenizer at 10,000 rpm for 2 h at room temperature to obtain a paste. Then vacuum-dry the paste for 3 h and roll-press it at 10 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a film; Immerse the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 1:2) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 3.55 mS cm -1 ,

[0054] The preparation method of the modified lignin (hereinafter referred to as LMA1) described in step (2) includes the following steps:

[0055] Mix enzymatic lignin and melamine in N,N-dimethylformamide according to the mass ratio of 1.03:1, where the concentration of enzymatic lignin in N,N-dimethylformamide is 0.065 g mL -1 , magnetically stir at 90 °C for 3.5 h, then add an N,N-dimethylformamide solution of aminotrimethylenephosphonic acid with a concentration of 0.40 g mL -1 . The mass ratio of enzymatic lignin to aminotrimethylenephosphonic acid is 1:2.31. Continue magnetic stirring for 9 h, cool to room temperature, stir for 30 minutes, wash with ethanol, and dry to obtain LMA1.

[0056] Example 8

[0057] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to the mass ratio of 1:1, where the concentration of hydroxyapatite in the solution is 0.0125 g mL -1 , magnetically stir at room temperature for 30 h, vacuum filter, wash, and dry for 10 h, then calcine at 350 °C for 2 h to obtain lithiated hydroxyapatite;

[0058] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix and disperse lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose in ethanol according to a mass ratio of 5:5:15:75, and stir with a homogenizer at 9000 rpm for 1 h at room temperature to obtain a paste. Then, vacuum-dry the paste for 3.5 h and roll it at 11 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with a uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a film; immerse the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 1:2) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 2.93 mS cm -1 ,

[0059] The preparation method of the modified lignin (hereinafter referred to as LMA2) described in step (2) includes the following steps:

[0060] Mix enzymatic lignin and melamine in N,N-dimethylformamide according to a mass ratio of 1:1.94, where the concentration of enzymatic lignin in N,N-dimethylformamide is 0.033 g mL -1 , and after magnetic stirring at 110 °C for 3 h, add an N,N-dimethylformamide solution of aminotrimethylenephosphonic acid with a concentration of 0.20 g mL -1 . The mass ratio of enzymatic lignin to aminotrimethylenephosphonic acid is 1:2.35. Continue magnetic stirring for 10 h, cool to room temperature, stir for 50 minutes, wash with ethanol, and dry to obtain LMA2.

[0061] Example 9

[0062] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to a mass ratio of 1:2, where the concentration of hydroxyapatite in the solution is 0.01 g mL -1 , magnetic stir at room temperature for 36 h, vacuum filter, wash, and dry for 11 h, and then calcine at 250 °C for 3 h to obtain lithiated hydroxyapatite;

[0063] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix and disperse lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose in ethanol according to the mass ratio of 15.6:4.4:15:65. Stir with a homogenizer at 10,000 rpm for 1.5 h at room temperature to obtain a paste. Then, vacuum-dry the paste for 2 h and roll-press it at 8 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with a uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a film. Immerse the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 1:1) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 2.64 mS cm -1 ,

[0064] The preparation method of the modified lignin (hereinafter referred to as LMA3) described in step (2) includes the following steps:

[0065] Mix enzymatic lignin and melamine in N,N-dimethylformamide according to the mass ratio of 1:1.46, where the concentration of enzymatic lignin in N,N-dimethylformamide is 0.087 g mL -1 , and after magnetic stirring at 60 °C for 2 h, add an N,N-dimethylformamide solution of aminotrimethylenephosphonic acid with a concentration of 0.43 g mL -1 . The mass ratio of enzymatic lignin to aminotrimethylenephosphonic acid is 1:2.66. Continue magnetic stirring for 6 h, cool to room temperature, stir for 55 minutes, wash with ethanol, and dry to obtain LMA3.

[0066] Example 10

[0067] (1) Mix hydroxyapatite powder and lithium fluoride in deionized water according to the mass ratio of 2:1, where the concentration of hydroxyapatite in the solution is 0.02 g mL -1 , magnetic stir at room temperature for 24 h, vacuum filter, wash, and dry for 12 h, then calcine at 350 °C for 2 h to obtain lithiated hydroxyapatite;

[0068] (2) Wash and dry the paste-like bacterial cellulose slurry with deionized water. Mix and disperse lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin, and the paste-like bacterial cellulose in ethanol according to the mass ratio of 10:10:15:65. Stir with a homogenizer at 10,000 rpm for 1 h at room temperature to obtain a paste. Then vacuum-dry the paste for 3.5 h and roll-press it at 9 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness, named BC / Li-FR polymer electrolyte, which exists in the form of a film. Immerse the polymer electrolyte in vinyl fluoride carbonate / ethyl difluoroacetate (v / v = 2:1) to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, named BC / Li-FR gel polymer electrolyte, which exists in the form of a film. The ionic conductivity of the BC / Li-FR gel polymer electrolyte at room temperature is 3.02 mS cm -1 ,

[0069] The preparation method of the modified lignin (hereinafter referred to as LMA4) described in step (2) includes the following steps:

[0070] Mix enzymatic lignin and melamine in N,N-dimethylformamide according to the mass ratio of 1.37:1, where the concentration of enzymatic lignin in N,N-dimethylformamide is 0.048 g mL -1 . After magnetic stirring at 90 °C for 4 h, add an N,N-dimethylformamide solution of aminotrimethylenephosphonic acid with a concentration of 0.60 g mL -1 . The mass ratio of enzymatic lignin to aminotrimethylenephosphonic acid is 1:3.47. Continue magnetic stirring for 8 h, cool to room temperature, stir for 40 minutes, wash with ethanol, and dry to obtain LMA4.

[0071] Comparative Example 1

[0072] Article title: Constructing flame-retardant gel polymer electrolytes via multiscale free radical annihilating agents for Ni-rich lithium batteries

[0073] Journal: Energy Storage Materials 50(2022)495 - 504

[0074] Authors: Tao Zhua, Guoqing Liu, Dongli Chena, Jinxuan Chen, Peng Qi, Jun Sun, Xiaoyu Gu, Sheng Zhang

[0075] Method: Through a one-step precipitation polymerization reaction, HCCP (hexachlorocyclotriphosphazene) and TA (tannic acid) were mixed in an acetonitrile solution, pyridine was added as an initiator, and after reacting for 12 hours, HT (hexachlorocyclotriphosphazene cross-linked tannic acid microspheres) was obtained through centrifugal separation, washing, and freeze-drying. HT, PEGDA (polyethylene glycol diacrylate), and Les (liquid electrolyte) were mixed, and after adding the thermal initiator AIBN (azobisisobutyronitrile), an in-situ polymerization method was used to react at 60 °C for 12 hours to form the PEGGPE@HT gel polymer electrolyte. The PEGGPE@HT gel polymer electrolyte was assembled into a battery, and the ionic conductivity at room temperature was 0.986 mS cm -1 , Li + transference number was 0.54.

[0076] Comparative Example 2

[0077] Article Title: Closo-Borate Gel Polymer Electrolyte with Remarkable Electrochemical Stability and a Wide Operating Temperature Window

[0078] Journal: Advanced Science 9(2022)2106032

[0079] Authors: Tao Zhua, Guoqing Liu, Dongli Chena, Jinxuan Chen, Peng Qi, Jun Sun, Xiaoyu Gu, Sheng Zhang

[0080] Method: LiBH4 (lithium borohydride) and B 10 H 14 (decaborane) were mixed and then put into a stainless-steel ball milling jar for ball milling. The ball-milled material was loaded into a stainless-steel Swagelok cell and annealed at 200 °C for 18 hours, and then ground into powder in an argon glove box. Li2B 12 H 12(Lithium dodecahydro-closo-dodecaborate) powder was added to anhydrous propylene carbonate and ultrasonically dispersed, then PMMA (polymethyl methacrylate) was added and stirred. The mixture was heated to 120 °C and maintained for 15 minutes to form a translucent yellow gel polymer electrolyte. The gel polymer electrolyte was assembled into a battery, and the ionic conductivity of the battery at 20 °C was 0.73 mS cm -1 , Li + transference number was 0.51.

[0081] This invention and Comparative Example 1 and Comparative Example 2 all belong to the field of gel polymer electrolytes. In Comparative Example 1, PEGDA, Les, HT and thermal initiator AIBN were used to form a PEGGPE@HT gel polymer electrolyte through an in-situ polymerization method of heating to initiate PEGDA; in Comparative Example 2, a gel polymer electrolyte was formed by a thermal-induced gelation method by heating a mixture of PMMA and PC; the raw materials and preparation methods used in this invention are different from those of Comparative Example 1 and 2, and the raw materials such as hydroxyapatite, bacterial cellulose and lignin used in this invention have lower costs, and the in-situ composite, physical mixing and gelation treatment methods are adopted, so the process is simple and easy to operate compared with Comparative Example 1-2. Compared with Comparative Example 1 and 2, the gel polymer electrolyte prepared in this invention has a nanofiber network with high porosity and a biomimetic plant cell wall structure, and its performance in terms of ionic conductivity, lithium ion transference number, etc. is superior to that of Comparative Example 1-2. In addition, compared with Comparative Example 1-2, this invention also has more excellent flame retardant performance, thermal stability, mechanical properties and high ionic conductivity at low temperature and other advantages. In summary: This invention breaks through the technical bottleneck that it is difficult to simultaneously improve any two, three or more properties such as flame retardant performance, electrochemical performance, room temperature and low temperature conductivity, thermal stability and tensile strength in the prior art. Compared with the prior art, this invention reduces costs, saves energy and protects the environment and simplifies the process by using natural ecological compounds, and simultaneously improves flame retardant performance, electrochemical performance, room temperature and low temperature conductivity, thermal stability and mechanical properties. In addition, the raw material ratios and process parameters used in each embodiment of this invention are different, and the properties of the obtained polymer electrolytes are also different. Generally speaking: The best excellent effect of the polymer electrolyte obtained in this invention is achieved by the synergistic regulation of raw materials, raw material ratios, processes and process parameters, and only within the scope of the claims of this invention can the best excellent effect be achieved.

Claims

1. Lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, characterized in that: Its preparation method comprises the following steps: (1) Mix hydroxyapatite powder and lithium fluoride in deionized water at a mass ratio of 1:5 to 5:1, wherein the concentration of hydroxyapatite in the solution is 0.01 to 0.1 g mL -1 , magnetically stirring at room temperature for 12 to 40 hours, vacuum filtering, washing, and drying for 5 to 20 hours, and calcining at 180 to 400° C. for 1 to 10 hours to obtain lithiated hydroxyapatite; (2) The paste bacterial cellulose slurry is washed and dried with deionized water, and lithium bis(trifluoromethanesulfonyl)imide, the lithiated hydroxyapatite obtained in step (1), the modified lignin and the paste bacterial cellulose are mixed and dispersed in ethanol in a mass ratio of 4.4-15.6:4.4-15.6:15:65-75, and a homogenizer is used to stir at a speed of 8000-10000 rpm for 0.5-2 hours at room temperature to obtain a paste, and the paste is vacuum dried for 2-3.5 hours and rolled at 8-11 MPa to obtain a lignin-based flame-retardant bacterial cellulose polymer electrolyte with uniform thickness; the polymer electrolyte is immersed in fluoroethylene carbonate / ethyl difluoroacetate to obtain a lignin-based flame-retardant bacterial cellulose gel polymer electrolyte, wherein the volume ratio of fluoroethylene carbonate to ethyl difluoroacetate is 1:2-2:1; the polymer electrolyte has a carbon residue rate of ≥49.52% and a heat release rate peak value of ≤61.12 kW m at ≥700°C. -2 , peak smoke release rate ≤ 0.0089m 2 s -1 , T5 ≥ 246.9℃, at room temperature, the ionic conductivity of the gel polymer electrolyte is 2.37~5mS cm -1 , lithium ion migration number ≥ 0.75, electrochemical window ≥ 4.87V (vs Li + / Li); at ≤-20℃, ionic conductivity ≥0.162mS cm -1 ; The modified lignin in step (2) is LNDP or LMA; The preparation method of LNDP comprises the following steps: Take sodium lignin sulfonate and add it to deionized water to make a concentration of 0.07-0.5 g mL -1 Add urea to formaldehyde to make a concentration of 0.2-1 g mL -1 urea formaldehyde solution, and then add the sodium lignin sulfonate aqueous solution to the urea formaldehyde solution and mix well, wherein the mass ratio of the sodium lignin sulfonate to the urea is 1:3 to 1:1, react at 25 to 100°C for 1 to 8 hours, cool, and add 0.5 to 5 mol L -1 HCl aqueous solution, adjust the solution to be weakly acidic, and then filter, wash with deionized water and dry to obtain LSN. LSN and p-hydroxybenzaldehyde are mixed in ethanol at a mass ratio of 1:2 to 1.1:1, wherein the concentration of LSN is 0.06 to 0.45 g mL -1 , keeping warm at 45-80°C for 0.5-5 hours, cooling, filtering, washing with ethanol, and drying to obtain LND powder; adding LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:2.5-2:1 to tetrahydrofuran, wherein the concentration of LND is 0.06-0.8 g mL -1 , react at 10-50°C for 6-30h, then filter, wash with tetrahydrofuran, and dry in vacuo to obtain LNDP; The preparation method of LMA comprises the following steps: The enzymatically hydrolyzed lignin and melamine are mixed in N,N-dimethylformamide at a mass ratio of 1:2.5 to 2.5:1, wherein the concentration of the enzymatically hydrolyzed lignin in N,N-dimethylformamide is 0.02 to 0.1 g mL -1 , after magnetic stirring at 50-150℃ for 1-8h, add 0.1-0.8g mL -1 A solution of aminotrimethylenephosphonic acid in N,N-dimethylformamide, wherein the mass ratio of enzymatically hydrolyzed lignin to aminotrimethylenephosphonic acid is 1:5-1:2, is continuously stirred magnetically for 2-15 hours, cooled to room temperature, stirred for 20-60 minutes, washed with ethanol, and dried to obtain LMA.

2. The lignin-based flame-retardant bacterial cellulose gel polymer electrolyte according to claim 1, characterized in that: In step (1), hydroxyapatite powder and lithium fluoride are mixed in deionized water at a mass ratio of 1:2 to 2:1, wherein the concentration of hydroxyapatite in the solution is 0.01 to 0.02 g mL -1 , magnetically stirred at room temperature for 24 to 36 hours, vacuum filtered, washed and dried for 10 to 12 hours, and calcined at 200 to 350° C. for 2 to 4.5 hours to obtain lithiated hydroxyapatite.

3. The lignin-based flame-retardant bacterial cellulose gel polymer electrolyte according to claim 1, characterized in that: The preparation method of LNDP described in step (2) comprises the following steps: Take sodium lignin sulfonate and add it to deionized water to make a concentration of 0.071-0.125 g mL -1 Add urea to formaldehyde to make a concentration of 0.25-0.50 g mL -1 urea formaldehyde solution, and then add the sodium lignin sulfonate aqueous solution to the urea formaldehyde solution and mix well, the mass ratio of the sodium lignin sulfonate to urea is 1:2.12 to 1:1.06, react at 30 to 65°C for 2 to 4 hours, cool, and add 1 to 2 mol L -1 HCl aqueous solution, adjust the solution to be weakly acidic, and then filter, wash with deionized water and dry to obtain LSN. LSN and p-hydroxybenzaldehyde are mixed in ethanol at a mass ratio of 1:1.2 to 1.1:1, wherein the concentration of LSN is 0.071 to 0.125 g mL -1 , keeping warm at 50-65°C for 1-3 hours, cooling, filtering, washing with ethanol, and drying to obtain LND powder; adding LND and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:1.85-1.08:1 to tetrahydrofuran, wherein the concentration of LND is 0.083-0.16 g / mL -1 , react at 10-25°C for 8-24h, then filter, wash with tetrahydrofuran and dry in vacuum to obtain LNDP.

4. The lignin-based flame-retardant bacterial cellulose gel polymer electrolyte according to claim 1, characterized in that: The preparation method of LMA described in step (2) comprises the following steps: The enzymatically hydrolyzed lignin and melamine are mixed in N,N-dimethylformamide at a mass ratio of 1:1.94 to 1.37:1, wherein the concentration of the enzymatically hydrolyzed lignin in N,N-dimethylformamide is 0.033 to 0.087 g mL -1 , after magnetic stirring at 60-110°C for 2-4h, add 0.2-0.6g mL -1 A solution of aminotrimethylenephosphonic acid in N,N-dimethylformamide, wherein the mass ratio of enzymatic lignin to aminotrimethylenephosphonic acid is 1:3.47-1:2.31, is continuously stirred magnetically for 6-10 hours, cooled to room temperature, stirred for 30-55 minutes, washed with ethanol, and dried to obtain LMA.

5. Application of the lignin-based flame-retardant bacterial cellulose gel polymer electrolyte according to any of claims 1 to 4 in the field of batteries.